1. Field of the Invention
A dynamic temperature control system for use with a fluid circulating system to control the temperature of fluid circulated therethrough.
2. Description of the Prior Art
Thermal blanklets and heating pads are well known in the art. Such thermal blankets commonly include either a cooling or heating effect. Generally heating blankets or pads incorporated the use of electrical resistance elements disposed thereout the area of the blanket. Similarly cold applicator pads or blankets used in the medical field frequently include a flexible plastic package containing two chemicals which when mixed together absorb heat. The chemicals are frequently packaged on either side of a rupturable membrane so that application of pressure to the exterior package ruptures the membrane and causes the fluids to mix and produces the heat absorbing reaction. Alternately, cooling pads may be used in combination with a compressor, refrigerant condensation and evaporator coils. It is obvious that this type cold pads or blankets are heavy and cumbersome.
Various efforts have been made to provide means to automatically heat or cool such thermal blankets or pads.
U.S. Pat. No. 3,967,627 shows an apparatus for selectively heating or cooling comprising a source of heat transferring liquid, an applicator pad adapted to be applied to an area including means defining a conduit for carrying the liquid through the pad, heat exchanger means to receive the liquid including thermoelectric diode means for producing heat when an electrical potential of one polarity is applied thereto and for absorbing heat when an electrical potential of the opposite polarity is applied thereto, pump means for pumping the liquid from the source through the heat exchanger means and the applicator pad and control circuit means including temperature-sensitive means responsive to the temperature of the liquid for controlling the polarity and duration of application of an electrical potential to the thermoelectric diode means under operator control. The apparatus wherein the temperature-sensitive means of the control circuit means comprises thermistor means arranged to sense the temperature of the liquid just prior to its entry into the heat exchanger means including adjustable resistive circuit means connected in circuit with the thermistor means controlled by an operator for generating a control signal representative of a difference between a desired operating temperature and the actual temperature of the liquid and semiconductor switch means responsive to the control signal for controlling the application of electrical energy to the thermoelectric diode means for bringing the temperature of the liquid to the desired operating temperature for the system.
U.S. Pat. No. 4,459,468 discloses a circulating system capable of producing both a heated and cooled fluid of various temperatures circulated to the thermal blanket at the desired "hot" or "cold" temperature. The system comprises a reservoir and a temperature transfer means to heat or cool fluid within the reservoir. A temperature sensor monitors the fluid temperature in the reservoir. A temperature control means is electrically connected in current regulating and activating relation to the temperature transfer means such that a continuous path of information flows between the monitored fluid and temperature control means and to the thermal modules for activation thereof in order to maintain the desired temperature.
U.S. Pat. No. 5,051,562 teaches a temperature controlled fluid circulating system for use with a fluid circulating system selectively operable in a first or second selected operating mode including at least one thermal module operable in heating or cooling state to monitor and control the temperature of fluid circulated through a remote liquid circulation manifold. The fluid circulating system comprises a display/control panel to select the system operating parameters including a selected operating temperature set point and a first sensor to sense the temperature of the fluid including means to generate a first temperature signal corresponding to the temperature of the fluid and a second sensor displaced adjacent the remote liquid circulation manifold including means to generate a second temperature signal corresponding to the temperature adjacent the remote liquid circulation manifold and a micro control including logic circuitry to receive signals from the display/control panel and the first and second temperature signals from the first and second temperature sensors respectively and to selectively generate thermal module control signals to control the heating or cooling of the thermal module by comparing the selected operating temperature set point with the temperature sensed by the first sensor when operating in the first selected operating mode to selectively generate the thermal module control signals and by comparing the selected operating temperature set point with the temperature sensed by the second sensor when operating in the second selected operating mode to selectively generate the thermal module control signals, the temperature controlled fluid circulating system further operable in an alternate operating mode wherein the logic circuitry further includes an alternate operating mode logic means such that the temperature controlled fluid circulation system operates in the alternate operating mode when in the second selected operating mode and the second temperature signal exceeds a first predetermined temperature range.